1. Field of the Invention
The present invention relates to the structure and manufacturing techniques of high density connector elements. More particularly the present invention relates to high density connector elements that are flexible and contain parallel conductors densely arranged on at least one surface.
2. Description of the Prior Art
As electronic circuitry becomes smaller and more densely populated with components, it is often difficult to interconnect separate electronic circuits using traditional soldering techniques. In many electronic assemblies, separate electronic components are placed in different areas of the assembly. Although the various electronic components will be near each other when the assembly is fully assembled, these same parts are kept apart while the assembly is dissembled. In order to electrically interconnect the various electronic components prior to the final assembly, a manufacturer often uses long connection cables to interconnect the various separated electronic components. The long connection cables are then folded up into the device as the separated electronic components are assembled. The use of such long cables is expensive, labor intensive and requires space in the final assembly to hold the folded long cables. Furthermore, the long cables often become pinched as they are folded up into the final assembly, thus causing defective assemblies.
Another solution to this problem, has been the use of elastomeric connectors. Elastomeric connectors are a class of contact connectors that contain conductive elements supported by an elastomeric body. By placing an elastomeric connector between two electronic components, the two components can be electrically interconnected as the final product is assembled and two electronic components are biased against the same elastomeric connector.
There are many different styles and designs of elastomeric connectors. The present invention addresses the family of elastomeric connectors that contain high density parallel conductors as part of their structure. In the prior art, many different manufacturing techniques have been developed to produce densely packed parallel conductors on a substrate. Such prior art techniques include the use of photo lithography, such as is exemplified by U.S. Pat. No. 3,421,961 to Joyce, entitled Method Of Making High Density Electrical Connections. Other techniques include chemical addition processes, where the conductors are plated onto a substrate, and plasma removal processes, where lines are removed from a conductive film on a substrate.
Although such prior art techniques work, they require very expensive manufacturing tools. Furthermore, due to the high dimensional tolerances needed, such prior art manufacturing techniques have a high rate of defective products that are scrapped.
Once high density conductors are produced on a substrate, that substrate can be cut into strips to produce high density flexible cables. Alternatively, the substrate can be wrapped around an elastomeric body to produce an elastomeric connector. Such elastomeric connectors are exemplified by U.S. Pat. No. 5,632,626 to Collins, entitled Retention Of Elastomeric Connector In A Housing and U.S. Pat. No. 5,588,845, entitled Connectors For Base Boards And Methods Of Connector For Base Boards. However, since these prior art elastomeric connectors are made with expensive high density parallel conductors, the prices of these elastomeric connectors are also high.
A need therefore exists for a new way to manufacture high density parallel connectors on a substrate that is low cost and does not require expensive manufacturing equipment. A need also exists for a method of producing high density parallel connectors in a more reliable manner. These needs are met by the present invention as described and claimed below.
The present invention is a high density connector element and its associated method of manufacture. The high density connector element contains a plurality of conductive wires that are arranged in parallel on the top surface of a flexible substrate. To manufacture the high density connector element, the flexible substrate is coated with an adhesive and wrapped around a cylindrical drum with the adhesive facing outwardly. Conductive wire is then wound around the cylindrical drum in a helical pattern. The conductive wire is densely wrapped around the flexible substrate on the cylindrical drum and is bound by the adhesive, thereby creating the high density connector element. After the winding is complete and the adhesive cured, at least one strip is cut from the high density connector element. The high density connector element has a flexible substrate and multiple conductive wires laid in parallel across the top surface of the substrate. Each of the conductive wires is electrically isolated from each of the other conductive wires, even when the wires are present in a highly dense pattern.
The high density connector element can be used to produce flexible cable connectors or can be used in the manufacture of elastomeric connectors.